Rods for welding cast iron, especially high grade cast iron



Dec. 10, 1963 c. c. ELSTE ETAL RODS FOR WE NG CAST 0N, PECIALLY HI GRADE'1 IR Filed Aug. 1960 FIG. I.

FIG. 3.

United States Patent The present invention relates to rods for weldingcast iron and, more particularly, to welding rods containing additionmaterial for effecting the welding of cast iron and steels without thenecessity of high temperature preheating procedures.

In the customary hot welding of cast iron, addition rods or Welding rodsare used to form a connecting seam with the cast iron which possess asimilar structure to that of the cast iron being welded. Cast ironprepared by machine casting in accordance with the usual industrialpractice has the following typical chemical analysis of alloyingmaterials:

Percent Carbon 3.0-3.5 Silicon 1.5-2.5 ldanganese 0.6-1.2 Phosphorus0.4-0.6 Sulfur 0.04-0.08

Nevertheless, slight deviations occur in the cast iron prepared as tothe content of alloying material noted above. The structure of the castiron, however, generally comprises graphite, perlite and ferrite. Theform in which the graphite is separated will depend upon the smeltingprocedure, the cooling and the silicon content. The Brinell hardnessvalue of such machine casting material normally ranges Within the HBlimits of 140-170 kg./mrn.

In accordance with machine casting procedures of the foregoing type,nickel or chromium may also be present in order to adjust and regulatethe degree of toughness and hardness of the cast iron to be produced.

in addition to the foregoing cast iron, refined types of cast iron maybe prepared having increased toughness as noted by the usual bendingtest. Such refined cast irons, however, possess lower phosphide contentand contain finely distributed graphite veins. For the most part, thegraphite veins are more uniformly distributed throughout the cast ironthan is found in cast iron prepared by the normal machine castingtechniques.

A further type of cast iron having a basic structure of perlite may beprepared in which the graphite is similarly finely distributed. Suchhigh grade perlite cast irons exhibit high tensile strength of 35 kg/mm.and higher, in consequence of their steel-like basic structure. Thechemical composition of such refined perlite cast iron may have thefollowing constituents:

Percent Carbon 2.5-3.0 Silicon 0.6-1.5 Manganese 0.5-0.8 PhosphorusAbout 0.1 Sulfur About 0.06

In addition, a spheroid cast iron may be provided in which the graphiteis formed in spherical shape. Nevertheless, the basic structure iscomposed of ferrite. The tensile strength of such spheroid cast ironranges from 50 to kgL/mmP. range between and 270 units. of this ferriticiron is as follows:

The Brinell hardness values may The chemical analysis 3,114,033 PatentedDec. 10, 1963 Percent Carbon 3.0-3.7 Silicon 2.2-2.6 Manganese 0.3-0.5Nickel About 1.0-1.8 Phosphorus About 0.1 Sulfur About 0.02 MagnesiumAbout 0.07

In welding cast iron parts, hot welding procedures afford the greatestcertainty that a desirable connection will be attained. Hot welding maybe executed by heating gas or electric current in the conventionalmanner. For this purpose cast welding rods are normally used which areprovided with a casting skin or covering, or even with grooves orrecesses filled with a flux material. Cast welding rods conventionallyused have the following typical composition:

. Percent Carbon 3.0-3.6 Silicon 2.8-3.8 Manganese 0.5-0.8 Phosphorus Atmost 0.6 Sulfur Less than 0.1

Carbon, Silicon, Manganese,

percent percent percent Electric arc welding 3. O 2. 6 0. 40 Gas welding3.1 2. 7 O. 38

The structureof the iron material in this regard consists of graphite,ferrite and perlite.

In the normal casting technique, the cast iron material is preheated toabout 600 C. and often to higher temperatures in order to give maximumeifect to the hot welding operation. The iron welding rod which servesas addition material or binding material possesses a considerably highersilicon content than that of the cast iron parts to be welded. Increasedsilicon content of 2.8 to 3.8% are normally used in order to promotegraphite formation upon welding. The weld traverses the interval fromthe melting temperature to the eutectoid value at 730 C. with respect tothe iron-carbon diagram considerably faster than does the cast ironduring its solidification in the casting mold. Hence, the increasedsilicon content is used for accelerating the graphite formation.

it is an object of the present invention to overcome the drawbacksencountered with respect to prior art welding techniques and to providean efiicient addition material for welding cast iron at lowertemperatures than were heretofore believed necessary.

Other and further objects of the invention will become apparent from astudy of the within specification and accompanying drawing, in whichFIGS. 1-4 illustrate schematic perspective views partially in section ofwelding rods in accordance with various embodiments of the invention.

in accordance with the present invention, it has been found that presentday cast iron may be welded with iron welding materials havingcompositions which vary with respect to the welding rod compositionscustomarily used in the past. The addition materials in accordance withthe invention may be applied for welding both thick and thin walled castiron parts advantageously without the requirement of a high temperaturepreheating step. Accordingly, the inherent stresses in the casting bodyare favorably accommodated and solid, stable unions are obtained inspite of the omission of a high temperature preheating step.

The welds which may be formed in accordance with the invention maydesirably contain in considerable measure ledeburitic structuralconstituents of white iron. Moreover, the Welds may also consist of amixed structure of ledeburite, perlite and graphite wherein the portionof graphite is generally below about 1.5%.

According to the Maurer phase diagram (Stahl-l-Eisen 44 (1924), No. 48,pp. 1522-1524, or Kruppsche Monatshefte (1924), pp. 115-122) for castiron, the above mentioned cast iron welds formed in accordance with theinvention vw' ll be found in the range of I, Ha and H at a total carboncontent of 1.5 to 2.5%, and a silicon content of 1.0 to 2.5%. Themanganese content will range within the limits of 0.3 to 1.2%. As may beappreciated by the artisan, nickel, chromium, aluminum and magnesium mayalso be added as desired.

Thus, a welding rod containing the addition material in accordance withthe invention, upon welding will yield a cast iron weld including agraphite content below about 1.5% and will contain:

Percent Carbon 1.5-2.5 Silicon -l 1.0-2.5 Manganese 0.3-1.2 Phosphorus0.02-0.2 Sulphur 0.02-0.l

A particularly suitable cast iron weld of the foregoing type found inpractice includes a graphite content of 0.2-1.2% and contains thefollowing:

This weld results in a structure which contains ledeburite as well asgraphite and penlite. The amount of graphite present will be between0.2-1.2% in dependence upon the rate of cooling. The Brinell hardness ofWelds of this type ranges between the values of 200-350 HB.Nevertheless, these values may be decreased by suitable heat treatmentto 170 HB.

The iron welding material which may be used in the form of cast ironwelding rods generally contains from 1.5 to 2.8% of carbon and from 0.3to 1.2% manganese.

Generally, for welding in accordance with the inven tion cast weldingrods may be used having approximately the following composition:

Percent Carbon 1.5-2. 8 Silicon 1.5-2.7 Manganese 0.3-1.2

Where gas welding is concerned, the welding rods in accordance with theinvention may preferably have approximately the following composition:

As a rule, these rods are welded with the cast iron parts in thepresence of a fluxing agent in powder or paste form in the usual manner.Nevertheless, the fluxing agent may pressed for the various ingredientsbe carried by the rod itself within a groove or recess therealong, or byproviding the flux agent as a covering for the rod itself.

As may be seen from FEGS. 1-4, welding rods in acc'ordance with theinvention may have a substantially rect'angular or circular crosssection. The rod 1 is provided with a recess for retaining the fluxagent 2, as shown in FIG. 1 and FIG. 4, or may be provided with a sheathof ilux agent 2 surrounding the inner core rod 1, as in FIG. 2.Alternatively, V grooves may be provided in the rod 1 for carrying theflux agent 2, as shown in FIG. 3.

In the case of electric arc welding, the rods in accord ance with theinvention may be formed of the same composition as those used in gaswelding procedures. Welding rods of cast iron may be similarly providedwith or wiiout a sheath or recess containing flux material. Moreover,the rod may be provided with a pressed-on iron-powder and graphitecontaining covering which is partially used up in forming the weld. Suchcovering, it will be appreciataed, effects a stable electric arc andmakes possible a reliable welding operation using either direct oralternate current.

In accordance with a preferred embodiment of the invention, a steel wirehaving 0.05 to 1.3% carbon, 0.03-0.5% silicon, O.10-1.5% manganese,0.02-0.07% phosphorus, 0.02-0.05 sulfur, may be used as a core wire uponwhich a covering containing the necessary carbon and silicon may bedisposed which will contribute the necessary ingredients during themelting and welding period.

The ingredients of such fluxes are 45% fiuorspar, 25 to 50% graphite, 5to 15%, rutile, 10 to 40% ferro-silicon of 45% silicon content (orequivalents), 5 to 10% ferro-titanium or 30% titanium content (orequivalent), 0 to 2% aluminum, 0 to 20% iron powder.

The thickness of the covering is preferably such that its outer diameteris about 1.1 to 1.5 times the diameter of the core.

Other constituents, such as aluminum and magnesium, for regulating thegraphitizing of the weld may be incorporated in the addition rods in aminor amount, i.e. 0.01-0.5%. Nickel for the purpose of increasing thetoughness of the Weld, and chromium, for the purpose of increasing thehardness, may also be incorporated in the Welding rod in amounts up to1.0% each, i.e. 0.ll%, and for chromium even up to 1.3

It will be appreciated that the addition welding rods in accordance withthe invention are suitable not only for forming welds of cast iron butalso for adding Wearresistant coating Welds upon cast iron surfaces.Besides erforming the welding operation by means of a gas flame or anelectric arc in the customary manner, the rods may also be Welded withthe application of protective gase such ar argon, helium, carbondioxide, etc, and mixtures thereof.

The Welds achieved in accordance with the invention are particularlysuitable for cast iron parts which may be subjected to exposure tostresses at high temperatures, even where a metal becomes red hot andthe exposure is over prolonged periods of time and is frequentlyrepeated. Generally, the welds in accordance With the in vention resistsuch stresses in the same manner as the base cast iron material. Aparticular advantage in ac cordance with the invention is the fact thateven with large and heavy cast iron parts, the conventional preheatingstep to temperatures of 600 C. and higher, may be omitted altogether, orelse only a slight preheating up to about 200 C. may be used.

In accordance with the foregoing,

preferably; 20 to the percentages er:- are percentages by weight and thecarbon, silicon, manganese, phosphorus, sulfur, nickel, chromium,magnesium and aluminum are expressed as additions to the basic cast ironmaterial which generally contains ledeburite, perlite and graphite.

Percent Carbon 1.5-2.8 Silicon 1.5-2.7 Manganese 0.3-1.2

Remainder substantially iron.

2. In the process of welding cast iron by applying an iron welding rodmaterial at welding temperatures to the cast iron surfaces to be welded,the step which comprises carrying out said welding by applying at thewelding temperature to the cast iron surfaces to be welded, after thereaching of a preheating temperature of at most about 200 C., an ironwelding material containing:

Percent Carbon 1.5-2.8 Silicon 1.5-2.7 Manganese 0.3-1.2 Phosphorus Q.0.02-0.07 Sulfur 0.02-0.05

Remainder substantially iron in the form of a welding rod containing asteelwire core having a carbon content of 0.05-1.3%, a silicon contentof 0.03-0.5%, a manganese content of 0..l-1.5%, a phosphorus content of0.02-0.07%, and a sulfur content of 0.02-0.05%, and a coveringcomprising carbon, silicon, and any manganese to complete the percentagerequired and at least one of nickel (0.01-1%) or chromium (0.1-1.3%).

3. In the process of welding cast iron by applying an iron welding rodmaterial at welding temperatures to the cast iron surfaces to be welded,the step which comprises carrying out said welding by applying at thewelding temperature to the cast iron surfaces to be welded, after thereaching of a preheating temperature of at most about 200 C., an ironrod welding material containing:

Percent Carbon -4. 1.5-2.8 Silicon 1.5-2.7 Manganese 0.3-1.2 Phosphorus0.02-0.07 Sulfur 0.02-0.05

Remainder substantially iron.

4. Improvement according to claim 3, wherein said welding materialadditionally contains 0.1 to about 1% nickel.

5. Improvement according to claim 4, wherein said welding materialadditionallycontains 0.1 to 1.3% chromium.

6. Improvement according to claim 5, wherein said welding materialadditionally contains a minor amount (0.01 to 0.5%) of at least one ofmagnesium or aluminum.

' 7. Cast iron welding rod material containing:

Percent Carbon 1.5-2.8 Silicon 1.5-2.7 Manganese 0.3-1.2 Phosphorus0.02-0.07 Sulfur 0.02-005 Remainder substantially iron wherein said rodincludes a steel wire core having a carbon content of 0.05-1.3%, asilicon content of 0.03- 0.5%, a manganese content of 0.10-1.5%, aphosphorus content of 0.02-0.07% and a sulfur content of 0.02- 0.05%,and a covering comprising carbon, silicon, and any manganese to completethe percentage required and at least one of nickel (0.1-1%) or chromium(0.1-1.3%).

8. Cast iron welding rod material according to claim 7 wherein saidwelding rod material has a flux of the following composition:

Percent Fluorspar 20-45 Graphite 25-50 Rutile 5-15 Ferrosilicon (45% Si)10-40 Ferrotitanium (30% Ti) 5-10 Aluminum i 0-2 Iron-powder 0-20References Cited in the file of this patent UNITED STATES PATENTS UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noo 3 ll l O33December 1O 1963 Curt Christian Elster et al.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 2. line 2 for "3.03,7" read 3.4-3.7 line 48 for "content" readcontents column 4. line 353 for "15%" read 15% column 5 line 36 for"0.0l-l%" read 0 ll% a,

Signed and sealed this 5th day of May 1964.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. IN THE PROCESS OF WELDING CAST IRON BY APPLYING AN IRON WELDING RODMATERIAL AT WELDING TEMPERATURES TO THE CAST IRON SURFACES TO BE WELDED,THE STEP WHICH COMPRISES CARRYING OUT SAID WELDING BY APPLYING AT THEWELDING TEMPERATURE TO THE CAST IRON SURFACES TO BE WELDED, AFTER THE